strange thing happened while driving home

[rocky5517]

2019 GT 3600 miles/ driving home last night, got caught in a bad rainstorm ( first time in rain). Was fooling around with cruise control. Thought I turned it off. The car started "surging", like I was stepping on the gas, except I wasn't. Sounded almost like it was downshifting. RPM's hardly moved. Car was behaving normally other than crazy sound of engine 'surging" or trying to downshift. At first I thought the wipers were making a weird noise. Came to a stop, switched exhaust modes, drive modes, put it in neutral, no improvement. Looked at the gauges- no check engine' everything normal except the air'fuel ration was bouncing from 14 to 20, which was the max. Started it this morning to go to the dealer and of course it was fine. Bringing it in for service next week. They weren't too concerned because no 'check engine light " came on.
Question # 1- could I have screwed up with the cruise control and never turned it off properly? Was the engine fighting the cruise control?
Question # 2- what exactly is air/fuel ratio, and is 20 ( the upper end of the range) normal? On way home from the dealer the air/fuel was agian bouncing from 14 to 20.
What do you think?

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[Nagare]

Even if cruise control was on, stepping on the gas would let you accelerate and once you took your foot off it would go back to the speed you set.

Air fuel ratio is the mix of...air and fuel. 20 is what you get off pedal basically, 14-15 is "ideal" for cruising, drops lower (12-13) if you're going WOT.

 

[ChromaticGrey]

14 while on the gas and 20 while engine braking are exactly where they should be. At least on my 2017. I think the 18 19 are the same.

Air fuel is exactly what it sounds like. The ratio of air to fuel. 14 would be 14 parts air to one part fuel that is in the combustion chamber. While at decel you dont need fuel, so it drops to 20 : 1. Although i think there isnt actually combustion going on during decel, and it should be almost no fuel being burned, someone more knowledge can answer that one.

As for question 1. Do you have an auto? Were you going down a relatively steep hill? Maybe it was holding gear to slow down?

 

[rocky5517]

14 while on the gas and 20 while engine braking are exactly where they should be. At least on my 2017. I think the 18 19 are the same.

Air fuel is exactly what it sounds like. The ratio of air to fuel. 14 would be 14 parts air to one part fuel that is in the combustion chamber. While at decel you dont need fuel, so it drops to 20 : 1. Although i think there isnt actually combustion going on during decel, and it should be almost no fuel being burned, someone more knowledge can answer that one.

As for question 1. Do you have an auto? Were you going down a relatively steep hill? Maybe it was holding gear to slow down?

Yes I should have mentioned I have auto. Road was level.

14 while on the gas and 20 while engine braking are exactly where they should be. At least on my 2017. I think the 18 19 are the same.

Air fuel is exactly what it sounds like. The ratio of air to fuel. 14 would be 14 parts air to one part fuel that is in the combustion chamber. While at decel you dont need fuel, so it drops to 20 : 1. Although i think there isnt actually combustion going on during decel, and it should be almost no fuel being burned, someone more knowledge can answer that one.

As for question 1. Do you have an auto? Were you going down a relatively steep hill? Maybe it was holding gear to slow down?

Yes I should have mentioned I have auto, and no, road was level

14 while on the gas and 20 while engine braking are exactly where they should be. At least on my 2017. I think the 18 19 are the same.

Air fuel is exactly what it sounds like. The ratio of air to fuel. 14 would be 14 parts air to one part fuel that is in the combustion chamber. While at decel you dont need fuel, so it drops to 20 : 1. Although i think there isnt actually combustion going on during decel, and it should be almost no fuel being burned, someone more knowledge can answer that one.

As for question 1. Do you have an auto? Were you going down a relatively steep hill? Maybe it was holding gear to slow down?

Yes should have mentioned I have automatic, and the road was really level

 

[Blue Moon]

Did it feel like you were hydroplaning? I rarely drive automatics, but your description of what happened sounds sort of similar to how my car acts when the tires lose grip on the water.

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